code: def testZero(self):
      self.assertEqual(DerivativeSFX()([0] * 100), (0.0, 0.0))
  
file_path: essentia/test/src/unittests/sfx/test_derivativesfx.py
imports: from essentia_test import *
  import numpy
label_desc: Use image node_id 2 for calling the TestDerivativeSfx obj's underlying member method code with example usage: obj.testZero() without return types